1. Field of the Invention
This invention relates to an analog display device, and more particularly to an analog display device having a plurality of display segments of any suitable shape, such as a bar shape, rectangle, polygon, circle or the like arranged in parallel to one another and adapted to accurately display a warning signal representing input data.
2. Description of the Prior Art
Recently, an analog display device has been extensively used, for example, for a fuel indicator, a thermometer or the like mounted on an instrument panel section of a dashboard of an automobile. Such an analog display device is constructed to display a warning signal of, for example, red to provide warning or caution representing input data, such as the residue of fuel oil, a temperature of a radiator or the like switching from a high range to a low range when magnitude of the input data is below a predetermined level.
Such a conventional analog display device is divided into three types. The conventional analog display device of the three types will be described in connection with a fuel indicator or gauge with reference to FIGS. 1 to 3.
The first type, as shown in FIG. 1, is to always illuminate display segments RS of warning color or red displaying a warning signal indicating that magnitude of input data is at a low level, together with display segments GS of green luminous color displaying a safety signal indicating the high level when the magnitude is below a predetermined level as well as the high level. The second type is constructed in such a manner as shown in FIGS. 2A and 2B. More particularly, it is adapted to illuminate display segments of green when magnitude of input data is above a predetermined level and display segments of red arranged at the left end when the magnitude is below the level, as shown in FIGS. 2A and 2B, respectively. The third type, as shown in FIG. 3, is constructed to vertically arrange two display scales S1 and S2 of the same color in parallel which serve to display a high level and a low level, respectively.
However, the conventional analog display device of such three types has such disadvantages as described hereinafter.
The first type is obliged to illuminate the display segments of warning color even when a warning signal is not required. The second type has a disadvantage that display of warning color significantly deviates from a position relative to a display scale for normal display. In order to minimize such disadvantages of the first and second types, there are generally provided two display segments RS of warning color. Nevertheless, in the analog display device of the first and second types, it is almost impossible to quantitatively indicate the degree of warning so that an observer may accurately notice the quantitative degree of warning. Also, the display patterns indicating the warning and the safety signals become unbalanced in design.
Further, the analog display device of the third type has a disadvantage that an observer cannot rapidly notice the degree of warning because the high and low levels are displayed on the respective display scales.